Mongodb schema and data migration lib
npm install @bitscheme/mgdb-migratorA simple migration system for mongodb supporting up/downwards migrations.
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| ------ | :-----------------------------------------------------------------------------------------------------------: |
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``sh`
$ npm i mgdb-migrator
or
`sh`
$ yarn add mgdb-migrator
`js
import { migrator } from 'mgdb-migrator'
await migrator.config({
// false disables logging
log: true,
// optional logging function
logger: (level, ...args) => console.log(level, ...args),
// migrations collection name defaults to 'migrations'
collectionName: 'migrations',
// max time allowed in ms for a migration to finish, default Number.POSITIVE_INFINITY
timeout: 30000,
// connection properties object
db: {
// mongodb connection url
connectionUrl: 'mongodb://localhost:27017/my-db',
// optional database name, in case using it in connection string is not an option
name: 'my-db',
// optional mongodb MongoClientOptions
options: {
useNewUrlParser: true,
useUnifiedTopology: true,
},
},
})
migrator.add({
version: 1,
name: 'Name for this migration',
up: async (client: MongoClient, logger: Logger) => {
// write your migration here
await client
.db()
.collection('albums')
.updateMany({}, { $set: { stars: 5 } })
},
down: async (client: MongoClient, logger: Logger) => {
// write your reverting migration here
await client
.db()
.collection('albums')
.updateMany({}, { $set: { stars: 0 } })
},
})
// run all configured migrations greater than the current version in order
await migrator.up()
`
Migration versions use sequential integers. Version 0 is reserved by migrator for initial state to indicate no migrations have been applied.
Migration state is implemented in the MongoDB collection migrations. It contains a single document used for locking migration control. Only one set of migrations is allowed to execute at a time.
> _You can override the collection name in config if needed._
`js`
{
_id: String, // 'control'
version: Int32,
locked: Bool,
lockedAt: Date
}
When a migration is performed, all migrations that include versions between current and target are executed serially in order.
For example, if you have added the following migrations:
- v1
- v2
- v3
- v4
and the current version is at v0, executing up(3) will run migrations v1, v2 and v3. If all migrations were successful, the current version becomes v3.
If any particular migration rejects or throws an error, subsequent migrations are halted and the current version is set to the last successfully completed migration.
See the Quick Start for options.
To setup a new database migration script, call migrator.add.
You must implement up and down functions. Return a promise (or use async/await) and
resolve to indicate success, throw an error or reject to abort.
To migrate to the latest configured migration:
`js`
migrator.up()
Or by specifying a target version, you can migrate directly to that version (if possible).
`js`
migrator.up(1)
To revert a migration:
`javascript`
migrator.down(1)
If you want to undo all of your migrations, you can migrate back down to version 0 by running:
`javascript`
migrator.down(0)
Sometimes (usually when something goes awry), you may need to retry a migration. You can do this by updating the migrations.version field in mongodb to the previous version and re-executing your migration.
To see what version the database is at, call:
`javascript`
migrator.getVersion()
To see the configured migrations (excluding v0), call:
`javascript`
migrator.getMigrations()
To close the mongodb connection, call:
`javascript`
migrator.close()
You can make use of the MongoDB Transaction API in your migration scripts.
Note: this requires
- MongoDB 4.0 or higher
migrator will call your migration up and down function with a second argument: client, a MongoClient instance to give you access to the startSession function.
Example:
`javascript`
const albumMigration = {
version: 1,
async up(client) {
const session = client.startSession()
try {
await session.withTransaction(async () => {
await db
.collection('albums')
.updateOne({ artist: 'The Beatles' }, { $set: { blacklisted: true } })
await db.collection('albums').updateOne({ artist: 'The Doors' }, { $set: { stars: 5 } })
})
} finally {
await session.endSession()
}
},
async down(client) {
const session = client.startSession()
try {
await session.withTransaction(async () => {
await db
.collection('albums')
.updateOne({ artist: 'The Beatles' }, { $set: { blacklisted: false } })
await db.collection('albums').updateOne({ artist: 'The Doors' }, { $set: { stars: 0 } })
})
} finally {
await session.endSession()
}
},
}
Migrations uses the console by default for logging if not provided. If you want to use your own logger (for sending to other consumers or similar) you can do so by
configuring the logger option when calling migrator.config.
Log levels conform to those in node.js Console API.
#### Winston example
`javascript
import { createLogger } from 'winston';
const logger = createLogger({
transports: [
new winston.transports.Console();
]
});
const myLogger = (level, message) => {
logger.log({
level,
message
});
}
migrator.config({
...
logger: myLogger
...
});
`
Run docker-compose to execute lib in dev mode
`sh`
$ npm run docker:dev
To configure a specific db connection for testing, create a .env file in the root of the project:
Example:
`sh`
MONGODB_URL=mongodb://localhost:27017/mgdb-migrator-test
Run docker-compose to execute lib in test mode
`sh``
$ npm run docker:test
Migration builds on percolatestudio/meteor-migrations with the goal of creating a generic mongodb migration library